Flow batteries for forklifts, new proton exchange membranes and sodium-ion cathode structures, and other potential breakthroughs

The Department of Energy’s ARPA-E program was created to give “blue-sky” research projects the money they need to prove whether or not they’re ready for commercialization. That includes a host of projects seeking to make batteries cheaper, smaller and more durable, whether to power electric vehicles, capture solar and wind energy, or balance the grid.

This year’s ARPA-E showcase outside Washington, D.C. featured a number of interesting battery technology projects on the cusp of real-world adoption. Here’s a sampling from a walk around the showroom floor, complete with photos.

The Flow Battery Fuel for Electric Forklifts. We’ve been covering the rise offlow batteries for grid energy storage applications, but what about flow batteries for electric vehicles? That’s the goal of an ARPA-E project from Argonne National Laboratory and Illinois Institute of Technology, that’s now led to a spinout company, called Influit Energy, that’s created a novel “nanoelectrofuel” (NEF) battery that could be small enough -- and powerful enough -- to meet the EV challenge.

In simple terms, Influit has figured out how to suspend nanoparticles of the electrochemically active materials that make up flow battery electrolyte in a water-based liquid, instead of dissolved salts that make up traditional flow battery electrolyte. That allows for a higher “loading” of energy per unit than today’s flow batteries can achieve, as well as a reduction in the weight of battery materials, John Katsoudas, CEO of Influit and IIT senior research associate, told me.

The NEF team first looked at mainline EVs as a target market, but decided to concentrate instead on a more mature electric transportation market: utility vehicles like forklifts, airport trucks, and other battery-powered fleets, he said. A pilot project is aimed at testing the NEF batteries at a Chicago-based airport, with a goal of delivering a battery that packs as much energy density as a lithium-ion battery, but can be “refueled” by replenishing spent electrolyte, rather than via a slower recharging process, he said.

Better Flow Batteries Through New Membranes. ITN Energy Systems, the Littleton, Colo.-based company that’s spun out such greentech companies as thin-film solar player Ascent Solar and tiny energy storage device makerInfinite Power Solutions, is now working on a vanadium redox flow battery system that could lower the cost of a critical piece of the flow battery puzzle: the proton exchange membranes that allow the conversion of flowing liquid into electricity.

Almost all flow batteries today use DuPont Nafion membranes, Ashutosh Misra, ITN’s executive vice president of business development, told me. ITN’sARPA-E project is seeking to prove that the company’s membrane technology, “based on the renewable biopolymer chitosan and ITN’s proprietary cross-linking process,” can beat Nafion on cost and performance terms, he said.

Membranes are an important part of the overall cost of the stacks that make up about 70 percent of a flow battery’s overall cost, he said. ITN is deploying its first-generation flow battery in Germany and California, and hopes to continue to lower costs by using next-generation electrolytes, such as the organic electrolytes being developed via ARPA-E funded projects at theUniversity of Southern California and Harvard University, he said.

Finding the Cheaper Alternatives to Lithium. Lithium-ion batteries are great for packing a lot of energy into a lightweight and compact form factor -- but lithium is a fairly rare metal with limited sources of supply.

Sharp Labs of America, the U.S. arm of the Japanese electronics (and solar) giant, is working on an ARPA-E project to replace expensive lithium with a much cheaper sodium-based electrolyte. Because sodium ions are much larger than lithium ions, they tend to break down battery electrodes faster, leading to lower rates of charging and discharging, and shorter cycle life.

Sharp Labs and partners University of Texas and Oregon State University have gone about solving that problem with a new cathode, using the chemical compound Prussian blue to create crystalline structures with larger interstitial spaces to accommodate the larger sodium ions.

Unlike other sodium-ion batteries that use an aqueous (water-based) electrolyte, such as those being developed by startups such as Aquion Energyand Alveo Energy, the Sharp Labs battery uses an organic electrolyte to forestall chemical decomposition and increase energy density and cycle life. The next steps for Sharp and its partners will be to prove out pilot-scale production of its electrode materials, and increasing the size of test batteries from coin cell size to pouch size -- still several steps from scaling up to grid-scale applications.